Old versions of Bitrix24 on premise (self-hosted) solution supported RTL, but the interface has been changed a lot since then. Please note that applying RTL to the current version of your self-hosted Bitrix24 may "break" your interface & result in problems. We may add RTL support for the self-hosted version in 2018.

I add the RTL function only when writing not in the interface , so in writing anywhere in the system ( tasks, chat, posts , comments ) , in web and in mobile application , the user can write Arabic , English in same phrase without any problem , and if anyone begin to write in Arabic it is directly use RTL , if write in English it use LTR exactly like facebook and WhatsApp . so it is not in the interface , only in text editor